Ash Barty stunned the sporting world on Wednesday by announcing her retirement from tennis, bowing out as the top-ranked player in the women's game.

The popular 25-year-old has not featured since winning her home grand slam at the Australian Open in January, becoming the first female Aussie singles champion of the tournament since Chris O'Neil in 1978.

Announcing the news on her Instagram page, Barty cited achieving a lifelong goal of winning Wimbledon last year as a primary factor behind her decision as well as being "spent physically".

But Barty is by no means the first sporting hero to retire at the top of their game. Below we take a look at some other examples of those who have exited as champions.

ALAIN PROST

The 1993 Formula One season was largely dominated by one man – Williams driver Alain Prost. The Frenchman had to battle hard with the iconic Ayrton Senna at the start of the campaign, with them each taking three wins from the first six races of the season. However, a run of four straight victories for Prost were followed by a string of retirements for Senna, ensuring a fourth world title that provided the ideal ending to a glittering career.

ALEX FERGUSON

One of the most successful managers in world football, Alex Ferguson began a 27-year stint at Manchester United after an excellent spell at Aberdeen. The Scot won 28 major trophies at Old Trafford, including 13 Premier League titles, five FA Cups and two Champions Leagues. His final trophy came with top-flight glory in 2012-13, and 17 days later he brought the curtain down.

PEYTON MANNING

Considered one of the greatest quarterbacks of all time, Peyton Manning won his first Super Bowl with the Indianapolis Colts in 2007 and, after an injury-blighted season that raised doubts about his ability aged 39, he added a second with the Denver Broncos in 2016, bowing out on the ultimate high.

RICHIE MCCAW, DAN CARTER

New Zealand became the first nation to successfully defend the Rugby World Cup trophy by beating Australia 34-17 in the final at Twickenham in 2015, adding to their success on home soil four years prior. It proved the end of the line for captain Richie McCaw, who was at the time the most capped player in rugby union with 148 appearances for the All Blacks, as well as mercurial fly-half Dan Carter. Ma'a Nonu, Conrad Smith and Kevin Mealamu were also among an influential contingent that opted to end their international careers.

PETE SAMPRAS

In defeating Andre Agassi in the final of the 2002 US Open, the same opponent he overcame to win his first grand slam 12 years prior, Pete Sampras secured his place among the greats in men's tennis. It was a then-record 14th major singles title for a male player for the American, a milestone that has since been surpassed by Roger Federer, Rafael Nadal and Novak Djokovic, but he did not compete again and announced his retirement almost one year later.

PHILIPP LAHM, MIROSLAV KLOSE

At 31 you still have a number of years ahead of you in football. However, after lifting the World Cup trophy with Germany in 2014, Philipp Lahm decided to call time on his international career and focus on club football with Bayern Munich. The versatile full-back made 113 appearances for his country and was joined by fellow centurions Per Mertesacker and Miroslav Klose – whose tally of 71 international strikes is a German record – in switching focus to domestic matters.

MARION BARTOLI

A first grand slam at Wimbledon in 2013 appeared to be the breakthrough moment for a 28-year-old Marion Bartoli, but reality proved very different. The Frenchwoman defeated Sabine Lisicki – who had overcome pre-tournament favourites Serena Williams and Agnieszka Radwanska – in the All England Club final, but announced her retirement during the Western and Southern Open just 40 days later due to persistent injuries. She attempted a comeback in 2018 but continued setbacks and injuries curtailed those plans.

NICO ROSBERG

Nico Rosberg had engaged in several intense battles with Lewis Hamilton before finally getting the better of his Mercedes team-mate to become Formula One world champion in the 2016 season. Still only 31, Rosberg had potentially several more years in F1 but the German instead opted to depart having reached the pinnacle of his sport.

Ash Barty has announced a shock retirement from tennis at just 25.

The Australian world number one revealed the surprising decision via her Instagram feed.

"I am so thankful for everything this sport has given me and leave feeling proud and fulfilled," she said.

"Thank you to everyone who has supported me along the way, I'll always be grateful for the lifelong memories that we created together."

Confirming the stunning news in an interview with close friend Casey Dellacqua, Barty revealed how achieving her dream of winning Wimbledon in 2021 led her to start considering retirement.

"It's something I've been thinking about for a long time," she said. "Wimbledon last year changed a lot for me as a person and for me as an athlete when you work hard your whole life for one goal and I've been able to share that with so many incredible people but to be able to win Wimbledon, which was my one true dream that I wanted in tennis, that really changed my perspective.

"I just had that gut feeling after Wimbledon and had spoken to my team quite a lot about it. There was just a little part of me that wasn't quite satisfied, wasn't quite fulfilled, then came the challenge of the Australian Open, that for me feels like my perfect way to celebrate what an amazing journey my tennis career has been.

"As a person this is what I want, I want to chase after some other dreams that I've always wanted to do."

Barty, who won her first singles grand slam at the French Open in 2019, has not played since winning the Australian Open final over Danielle Collins in January, and bids farewell to the sport knowing she has exhausted all of her physical energy.

"I just know that I am spent, physically I have nothing more to give," added Barty.

"That for me is success. I've given absolutely everything I can to this beautiful sport of tennis. I'm really happy with that. That is my success.

"Ash Barty the person has so many more dreams that she wants to chase after that don't necessarily involve travelling the world, being away from my family, being away from my home, which is where I've always wanted to be.

"Now I think it's important I get to enjoy the next phase of my life as Ash Barty the person, not Ash Barty the athlete."

Ash Barty has announced a shock retirement from tennis at just 25.

The Australian world number one announced the decision via her Instagram feed.

"I am so thankful for everything this sport has given me and leave feeling proud and fulfilled," she said.

"Thank you to everyone who has supported me along the way, I'll always be grateful for the lifelong memories that we created together."

Barty has not played since winning the Australian Open final over Danielle Collins in January.

Shelby Rogers continued her recent good form as she won an all-American clash with Amanda Anisimova in the first round of the Miami Open.

Rogers beat 10th seed Jelena Ostapenko en route to the third round at Indian Wells, where she lost in three sets to last year's US Open finalist Leylah Fernandez.

Both Rogers and Anisimova have experience of going into the second week of a grand slam, yet it was the more experienced Rogers who had the edge in South Florida, prevailing 3-6 6-0 6-3 in a stirring comeback.

Speaking on-court after the win, Rogers highlighted the challenge Anisimova poses when she is in form.

"[Anisimova] can come out and dictate play like nobody else when she is on fire, it's hard to do anything," she said.

"I felt like I had to counter that a little bit better. I was a little passive in the first, just running side to side.

"She played incredible. I'm just really happy I closed it out because I knew she was going to raise her level again at the end."

Round two will see a reunion between Rogers and Ostapenko, while Simona Halep, a two-time semi-finalist in Miami, will face Australia's Daria Saville.

Saville, formerly Daria Gavrilova, was ranked as high as 20 back in 2017, but had surgery on her Achilles last February.

A run to the last 16 at Indian Wells, including a top-10 win over Ons Jabeur, delivered a reminder of her quality and she will have the chance to claim another big-name scalp after beating Greet Minnen 7-5 6-3.

Elsewhere in the first round, there were wins for Marta Kostyuk, Magda Linette and Ekaterina Alexandrova.

Kaia Kanepi booked a second-round meeting with Sara Sorribes Tormo, while Heather Watson ended her six-year losing streak in Miami and will next face 15th seed Elina Svitolina.

Iga Swiatek claimed back-to-back WTA 1000 titles as she captured the Indian Wells Open crown after defeating Maria Sakkari 6-4 6-1.

Winning her 11th successive match, the Pole added to her triumph in Doha last month after prevailing in one hour and 20 minutes.

Swiatek subsequently climbed to a career-high second in the WTA rankings; making her the first Polish player to do so since Agnieszka Radwanska in July 2012.

The 20-year-old also claimed her fifth career title; becoming only the fifth woman to reach that tally before her 21st birthday after Kim Clijsters, Venus Williams, Serena Williams and Svetlana Kuznetsova.

"After playing so well in previous tournaments, I didn’t know it was possible for me to play that well for that long," said the former French Open champion, who claimed her second successive win over Sakkari having also prevailed in the Qatar Open semi-finals.

"I want to congratulate Maria. Every match against her is a great battle. I know that we've already started a cool rivalry. 

"I think it's going to last for 10 more years, so it's going to be exciting, and I’m sure we're going to play many more finals.

"I want to thank my team; they're doing an amazing job calming me down and getting me to the place where I'm more confident and developing my tennis."

The two finalists struggled to settle during the opening set; both hitting five double-faults as six of the first seven games went against the serve.

But 12 unforced errors to her opponent's seven proved crucial for Sakkari, who had only been broken seven times in her five previous matches, as third seed Swiatek drew first blood after 45 minutes.

Losing only her second set of the week, sixth seed Sakkari had been beaten on all three occasions in 2022 when losing the opener.

Meanwhile, Swiatek had not dropped a set since her fourth-round victory over Angelique Kerber, and built on that momentum as she dominated the second.

The former Roland Garros champion broke her opponent twice more, as she only required an additional 35 minutes to wrap up victory; a sweeping forehand sealing the deal.

Two top-ten talents have booked a date in the Indian Wells Open semi-final after Maria Sakkari and Paula Badosa won their quarter-finals in straight sets. 

First up, world number six Sakkari took on Ukrainian Elena Rybakina, prevailing 7-5 6-4.

Rybakina won the first three games of the match, working her way to an early 4-1 lead, before her Greek opponent rattled off six of the next seven games to claim the first set.

Sakkari again faced adversity early in the second set, coming back from 40-0 down in the second game to hold serve, before breaking the very next game to pinch the match-winning lead.

Former world number one Simona Halep emphatically dispatched unseeded Petra Matric 6-1 6-1 in Wednesday's quarter-final at the Indian Wells Open.

Halep landed 75 per cent of her first-serves and won those points at a rate of 82 per cent (27/33).

Martic's serve commanded much less respect, as she landed 69 per cent of her first-serves, but only won 36 per cent of those points (8/22).

After holding in her first service game, Martic allowed Halep to rattle off six consecutive games, with three double-faults assisting her Romanian opponent.

With the win, Halep booked a semi-final matchup against Poland's number three seed Iga Swiatek after she prevailed in her meeting with American Madison Keys in similar fashion.

The Grand Slam Board has announced that first-to-10 tie-breaks will conclude the final sets of all four majors with immediate effect.

Starting with May's French Open, the decision is being adopted on a trial basis with the aim of providing "greater consistency" to the rules when matches go the distance.

Prior to Wednesday's announcement, the French Open, Australian Open, US Open and Wimbledon each had their own rules when games went to a deciding tie-break.

The Australian Open is the only grand slam to already employ the first-to-10 rule at 6-6.

Wimbledon previously played first-to-seven at 12-12, while the US Open played a first-to-seven at 6-6.

There has not previously been a deciding tie-break at Roland-Garros, with all matches continuing until a player secured a two-game lead in the decider.

A statement released on behalf of Grand Slam Board members Jayne Hrdlicka, Gilles Moretton, Ian Hewitt and Mike McNulty confirmed the changes.

It read: "The Grand Slam Board's decision is based on a strong desire to create greater consistency in the rules of the game at the Grand Slams, and thus enhance the experience for the players and fans alike.

"This trial, which has been approved by the rules of the tennis committee governed by the ITF, will apply to all Grand Slams across qualifying, men's singles and doubles, women's singles and doubles, wheelchair and junior events in singles, and will commence at the 2022 edition of Roland-Garros."

The rule change will be reviewed after a full Grand Slam year and will remain in place should it be deemed a success.

The tweaks to the current format will ensure no repeat of John Isner's marathon battle with Nicolas Mahut at Wimbledon in 2010, which the American edged 70-68 in the final set of their first-round match.

Paula Badosa went a step closer to defending her Indian Wells Open title as she ended Leylah Fernandez's run to reach the quarter-finals.

Badosa was calm under pressure against last year's US Open runner-up, saving five out of the six breakpoints she offered up in a 6-4 6-4 success.

Matters were less routine for third seed Iga Swiatek, who held her nerve to come back from a set down against three-time major champion Angelique Kerber.

Breakpoints were contested in six of the match's first eight games and Kerber made the big points count, but Swiatek went on to triumph 4-6 6-2 6-3.

Swiatek, 20, showed grit beyond her years as she broke Kerber's serve four times in the second set, cleaning up her first-serve percentage while the German was only able to win 31 per cent of her successful first-serves (4-13).

Both women hit over 70 per cent of their first-serves in the final set, with the difference coming down to the return game, where Swiatek won half of her return points (12-24), with Kerber struggling (5-22).

Swiatek will face American Madison Keys, who defeated Harriet Dart in a brisk 69 minutes, while Badosa goes up against Veronika Kudermetova, who overcame Naomi Osaka in contentious circumstances earlier in the tournament.

WTA chairman Steve Simon declared Russian tennis players must not be penalised for their country's "authoritarian leadership" amid concerns they could be frozen out of top tournaments.

The ATP and WTA tours decided Russian and Belarusian players should not be allowed to represent those nations while the crisis in Ukraine continues, with stars such as Daniil Medvedev currently playing under a neutral flag.

The respective tennis tours have also cancelled plans to visit Russia in the near future.

United Kingdom sports minister Nigel Huddleston suggested on Tuesday that US Open champion Medvedev and fellow Russians could be blocked from playing at Wimbledon unless they make a stand against president Vladimir Putin.

But WTA head Simon insisted Russian and Belarusian tennis players should be able to continue featuring on the tour, despite a number of other sports banning such athletes.

"I can tell you that we have never banned athletes from participating on our tour as the result of political positions their leadership may take," Simon told BBC Sport.

"So it would take something very, very significant for that to change, but again we don't know where this is going."

If national governments impose preventive measures on Russian and Belarusian stars, Simon acknowledged there is little he can do to combat such rulings.

"I feel very, very strongly that again these individual athletes should not be the ones that are being penalised by the decisions of an authoritarian leadership that is obviously doing terrible, reprehensible things," Simon said.

"We are hopeful that they will refrain from that because I think there are an awful lot of other issues that go with it. I'm hoping that we continue with the sanctions, we continue doing everything we can to get peace, but again these people are the innocent victims of that, and being isolated as a result of these decisions I don't think it's fair."

Daniil Medvedev and fellow Russian tennis stars could be banned from playing at Wimbledon unless they denounce president Vladimir Putin.

That was confirmed by UK sports minister Nigel Huddleston on Tuesday, as he told a parliamentary committee there were concerns about Russian representation in sport.

With Russia's military invasion of Ukraine ongoing, Huddleston warned it would not be appropriate for anyone to be seen to be flying the flag for their homeland, or showing any support for Putin's regime.

Speaking at a Digital, Culture, Media and Sport Committee session, Huddleston was asked about Wimbledon and Medvedev, the current men's world number one player and reigning US Open champion.

Huddleston said: "We are looking and talking to various sports about this and what the response and requirements should be there. Absolutely, nobody flying the flag for Russia should be allowed or enabled."

He added: "We need some potential assurance that they are not supporters of Vladimir Putin and we are considering what requirements we may need to get some assurances along those lines.

"In short, would I be comfortable with a Russian athlete flying the Russian flag? No."

Asked about the All England Club, which hosts Wimbledon, Huddleston said: "We are in discussions."

Russia has four players in the men's top 30, and three in the women's top 30.

They are playing under neutral flags at present, after the ATP and WTA tours decided Russian and Belarusian players should not be permitted to represent those nations while conflict continues in Ukraine.

Wimbledon runs from June 27 to July 10 this year, with a week of qualifying preceding the tournament.

Demanding each player from Russia directly comes out against president Putin would be going a step beyond what is currently required.

Huddleston said: "We are looking at this very issue about what we do with individuals, and we are thinking about the implications of it, because I don't think people would accept people very clearly flying the Russian flag, in particular if there is any support and recognition for Putin and his regime."

Speaking last week at Indian Wells, Medvedev spoke about being allowed to continue to play on the tour.

"It's definitely not for me to decide. I follow the rules. I cannot do anything else," he said. "Right now the rule is that we can under our neutral flag.

"I want to play my favourite sport. Until I have the chance to do it, I'm going to be there to try to play for the fans, play for other people, for myself also of course.

"Also I think tennis is a very individual sport, so far what we are seeing [being sanctioned] are more national teams or some team sports. Let's see how the situation evolves."

World number five Anett Kontaveit slipped out of the Indian Wells Open after a 3-6 7-5 7-6 (7-5)  loss to Marketa Vondrousova.

Kontaveit was the second-highest seed remaining in the tournament entering Monday's play, and appeared to be on her way through to the fourth round after breaking twice in the opening set.

Yet Vondrousova got the better of her Polish opponent in a topsy turvy second set, forcing a decider that starter in frantic fashion, with a concession of serve in each of the opening five games.

Vondrousova held to end that street yet was pulled back to 4-4 by a resurgent Kontaveit, though the Czech world number 33 eventually closed the match out at the fourth time of asking in the tie-break to tee up a clash with Veronika Kudermetova.

Russia have been replaced by Serbia in the Davis Cup and Australia in the Billie Jean King Cup, the International Tennis Federation (ITF) has confirmed.

Russia, who won both competitions in 2021, have been suspended from competing in international team events following the country's invasion of Ukraine.

As the highest-ranked losing semi-finalist from last year, Serbia will take Russia's place in the Davis Cup Finals.

The wild card previously handed to Serbia will now go to one of the 12 nations knocked out in the qualifiers that took place earlier this month.

Likewise, as the highest-ranked side among the 2021 losing Billie Jean King Cup semi-finalists, Australia will replace Russia in that competition.

Australia were due to take part in April's qualifiers, but opponents Slovakia will now receive a bye and advance directly to the Finals.

Belarus have also been barred from competing in both events, meaning Belgium will receive a walkover in their qualifying match and advance to the Billie Jean King Cup Finals.

Emma Raducanu knows she must "get stronger" after losing to Petra Martic in the third round of the Indian Wells Open.

Martic came from a set down to beat US Open champion Raducanu 6-7 (3-7) 6-4 7-5 on Sunday.

Teenager Raducanu has been troubled by a back injury and an issue with her hip.

The Brit says she was hampered at Indian Wells, but is confident she will be fit for the Miami Open next week.

"I think it's just part of not playing and having so much stop start and having five, six days to prepare for matches and then playing at that intensity,” she said.

"It was a tough one not being able to serve full out so I was having to work so hard just to hold.

"I've just got to get stronger. I've had it for the last few days, just a product of training hard and probably the last match was pretty intense too and it didn't settle down.

"When you are crossing your fingers to hold serve every time, it's tough. I couldn't really drive up and I was kind of struggling to turn and reach.

"The margins were so small. I should be good for Miami, for sure."

Andy Murray has expressed his sympathy for Naomi Osaka over the abuse she was subjected to at Indian Wells but says athletes must deal with it.

Osaka was reduced to tears as she crashed out of the Indian Wells Open with a 6-0 6-4 third-round defeat to 21st seed Veronika Kudermetova on Saturday.

A member of the crowd could be heard shouting "Naomi, you suck" after the four-time grand slam champion had been broken in the first game of the match.

Osaka approached the chair umpire to report the incident and held further discussions with the court supervisor after being insulted again.

Murray says there is no place for such conduct, but believes players must be able to ignore it.

He said: “It's a difficult one. I've often thought watching certain sports, I wouldn't say I've often seen it loads in tennis … but if I watch a football or a soccer match and a player's going to take throw-in or a corner kick and the crowd are just hurling insults at those individuals.

"I always think, how is that allowed? Like, you can't do that. If you're doing that to someone when you're walking down the street or in any other sort of work environment, that's obviously not tolerated.

"I've played in certain atmospheres as well myself in tennis, like Davis Cup atmospheres, away from home, especially where the atmosphere's intense, and sometimes things are said and it's not that comfortable.

"The people that come to watch, you want them to be there and supporting the players and not making it more difficult for them. I don't know, but it's also something that's always just kind of been part of sports as well."

He added: "If you go and watch a basketball match, for example, and a player's taking free throws, I would say like almost every basketball match I've been to one of the players has been heckled by the crowd as well

"While it's wrong for those individuals to be doing it, the athletes obviously have to kind of be used to that as well or be able to deal with that too, even though it's not pleasant.

"I feel for Naomi, that obviously it upset her a lot, but it’s always been something that's been part of sport, I guess, as well.

"You have to be prepared for that in some ways and be able to tolerate it because it does happen regularly across all sports."